Additive for gasoline and diesel fuels



United States 2,864,675 ADDITIVE FOR GASOLINE AND DIESEL FUELS James W. .lean, Altadena, Calif, assignor, by direct and mesne assignments, of fifty-one percent to A. R. Chandler, thirty-two percent to John N. Adams, and seventeen percent to Stanley Turner No Drawing. Application October 24, 1955 Serial No. 542,508

12 Claims. (Cl. 44-50) This invention relates to an addition agent for fuels for internal combustion engines of both the spark ignition type and the diesel type, and more particularly to hydrocarbon fuels boiling in the gasolineboiling range and to diesel fuels.

1 This application is a continuation in part of my copending application, Serial No. 314,569, filed October 13, 1952, for improvements in Additive for Both Gasoline and Diesel Fuels, and now abandoned.

The usual additive for fuel for. internal combustion engines is not adaptable for both gasoline and diesel fuels.

sive travel of the ignition or so-called flame front throughout the mass of fuel within the engine cylinder, and therefore reducing the tendency toward explosion simultaneously through the mass of the fuel, would not be useful in non-spark ignition engines, such as diesel engines, where ignition and explosion of the fuel are brought about by the heat of compression of the air. instead, such an anti-knock agent for gasoline would have an effect just the reverse of what is desired in diesel fuels.

It is an object of this invention to produce an ad-i ditive for motor fuels which gives substantiallythe sameimprovement in the.operation of the engine, irrespective of whether the engine is of the gasoline type or the diesel type. Among the advantages of my additive with both types of engine are case of starting, suppression of carbon deposition, elimination of gum formation, marked smoothness in operation and increased power output.

Diesel fuels are often not so highly refined as gasoline fuel and'therefore are frequently attended by foul odor,

due in part at least, to the presence of sulfur compounds.

manufactured and sold as containing 44% of nitrogen,

there are added four ounces of dry sodium hydroxide. There is then added a liquid mixture consisting of 1300 cc. of isopropyl alcohol, 1300 cc. of methyl ethyl ketone and 130 0;cc. of a petroleum distillate fraction such .as that sold under the trade name Amsco-Solv A-80, said petroleum distillate fraction being commonly used as, a solventfor paint thinners because of its high content of aromatic hydrocarbons, this particular distillate fraction having an A. P. I. gravity of 40.5, and an initial boiling point, by the A. S. '1, M. distillation method, of 2l3 F., an end point of242 F and an aromatic For example, an additive for gasoline to improve. its anti-knock characteristics by causing a more progres-' hydrocarbon content, as shown by its aniline point, of

"ice

77%, most of which aromatic content being reported by said companys laboratory as toluene. The mass is then stirredand allowed to stand at room temperature I until it has attained a color throughout its entire mass ranging from a medium to dark red, depending upon.

time of standing andtemperature of the room -usually; J

from 24 to 48 hours. It will be noted that no heatisapplied and that no water is present except such traces of moisture asmay exist in the ingredients employed: As the reaction proceeds color changes take place, a pale cream color rising. at the beginning from the urea and sodium hydroxide up into the liquid mass and the liquid'mass finally becoming a clear dark red solution with some reddish flocculent material suspended in lit. The red solution with its aforesaid flocculent suspendedmaterial is drained off from excess urea and sodium hydroxide that remain in the bottom of the vessel. The red: solution is then filtered to remove the reddish floc-- culent material, which latter is a red amorphous powder. The clear dark red solution is a very stable materialand constitutes the additive obtained from rthematerials of this example which I employ for both gasoline and diesel fuels. It is substantially completelysoluble' in all grades of petroleum motor fuels, from gasoline on" through the various grades of diesel fuels.

Just what chemical reaction takes'place intheformationof the red liquid which comprises this additive has not been definitely determined. No gas bubbles arise, during the process, indicating that no free ammonia 'or other gaseous substanceis formed. Both the product and the reaction involved have definite characteristics. When prepared in the aforesaid manner substantially all of the clear red liquid is oil soluble. When water is. addedto this red liquid no clear solution isformed. Instead, it becomescloudy', and upon standingthe water settles to the bottom; If before filtering out-,thesolids as above explained a relatively large volume of water is added and shaken, the solids will dissolve'and a two-' phase system formed, an oily layer forming at the top.-.

Upon removing this top layer and letting the remainder stand at room temperature some entrainedwater will; settle to the bottom, leaving the clear red liquid. It, would thus appear thatv the red liquid. is substantially insoluble in water. In view of the fact that the urea, the sodium hydroxide, the isopropyl alcohol and the methyl ethyl ketone are allwater solublethis non solubility in water of the resulting red liquid is an unexpected property. When the red liquid isevaporated-to, dryness, white, long, fiat crystals are left which have a distinct'pattern. A mass spectrometer examination; of the red liquid made in accordance with the above example. showed'a methyl ethyl ketone content of. only 3.5% (from an original 33 /3 an increasejin theiso propyl alcohol content to 40.8% (from an original 33% and a toluene content of only 7% whereas the 33%% of Amsco Solvent A ingredient originally con tained around 77% of toluene, and with unknown com-;

pounds representing 48% of the sample subjected to the mass spectrometer examination. It is believed that-urea adducts are not formed, For one thing such adducts are not understood to beiformed when the material of' the aforesaid example are employed with urea Moreover, the presenceof sodium hydroxide is not understood tobe conducive to the formation of urea adducts;

also, the aforesaid non-solubility in water is contrary to e line and all grades of diesel fuel. When, however, the

have ended as water-soluble instead of oil-soluble.

solvent is not presentalong with the four ingredients a reddish liquid is formed, butit is not completely soluble in the gasoline or diesel fuels. On the other hand from 75 to 80% of it is water soluble. This suggests that the solvent does not enter the reaction but plays some part in taking up (dissolving) an intei mediate reaction product during the progress of the reactions, which intermediate product, in the" absence of the solvent, would In the complete absence of a solvent the relatively small amount of the red liquid formed which is soluble in the motor fuels may be separated from the water-soluble product and used as the additivefor motor fuels. Again, when the solvent is not present during the reaction that takes place betweenjthe urea, sodium hydroxide, alcohol and ketone such red liquid as isforined is'accompanied by the 'formatio'n'of crystals along the sides'of the vessel which are ofhpale yellow color. Thesecrystals are water-soluble, 'formin'g'aleinon colored solution but are not'soluble in' gas'oline. Theydo not'form when the solvent is present. Instead, the aforesaid flocculent material forms-and "is suspended inthered liquid and upon separation by filtering becomes an amorphous red powder.- Thisamorphous red material" is water soluble but is not soluble in' gasoline orother petroleum products.

If either the alcohol or theketone is omitted the re sults will -bedifie'rent from those which are obtained between the urea, sodiumhydroxide-alcohol and ketone for the aforesaid'conditions, i. e. atroom temperature (no heat added and with no water added. This is true whether'or not thesolvent is also present. If the ketone is omitted (the alcoholbeingpresent) a reaction proceeds which is slower than when the ketone is also present and a yellowish (instead of red) colored liquidresults which is mostly water-soluble, less than half of it being soluble in gasoline. When the alcohol is omitted (the ketone beingpresent) the-action produces a red colored liquid but again it is mostly wat er-soluble less than half of it being soluble in-g'asoline. 'Withfthe solvent beingalso present during the process less of the liquid product formed is water-soluble andgrnore of it is soluble in gasoline, but it is not entirely-soluble 'in' gasoline as in the case where both the ketone' -and the alcoholare present.

What reaction takes place'between the urea, sodium hydroxidegand alcohol (ketone not present): with out thepresence of a solvent, is "not "known.

Whereasin the formationof my additive no water is presenter is added as a separate material, itis possible that small amounts of watenpresent in-the materials'usd may influence or start the reaction. The: alcohols which I have'ernployed' havei b'eenof the 98% grade (2% water). Also, tothe extent that true aldol condensation maytake place withrespect 'to the ketone or other ingredicnts some water 'would be liberated that might perhaps influence the reactions."

Other alcohols may be employed than that-of the aforesaid example. While I have obtained excellent results with isopropyl alcohol and prefer to'employ it in the production of 'the additive, l havc experienced satisfactory results when there was substituted for the iso propyl alcohol the following alcoholspnormal propyl, normal butyl, isobutyl, secondary butyl, tertiary butyl and normal, secondary and tertiaryhmyl-in other words, anyof the alcohols containing from'3 to 5 carbon atoms. While ethyl alcohol may also beemployed, it tends to pick up water andis difficultto separate.

Likewise I am not limited to the methyl ethyl ketone of the preferred embodiment of my invention, and have substituted other ketones therefopwith satisfactory results. For example, in using 'acetonecyclohexone or methyl isobutyl ketone, I have obtained aclear liquid of somewhat darker red color than with methyl ethyl ketone but one which gave satisfactory performancea's an additive for both gasoline and diesel fuels. Aldehydes may be substituted forthe kctones. For cxamplegacetalde or with- Cal 4 hyde with isopropyl alcohol gave a product which, althoughslightly different in appearance from that produced when methyl ethyl ketone was used, was the characteristic red color and worked satisfactorily.

The solvent that may be employed along with the alco hol and ketone to form the three-component liquid mixture to be contacted with the urea and alkali metal hydroxide is susceptible of wide variation. Solvents of difierent aromatic hydrocarbon contentthan that of the paint thinner solvent whose gravity and boiling points are specified in the aforesaid example, have been employed with satisfactory results. Petroleum distillate fractions having an aromatic hydrocarbon content as shown by their aniline point, as low as 50%, may be employed as well as those with an aromatic hydrocarbon content of 98%. Petroleum distillate fractions with an aromatic hydrocarbon content falling within this suitable range are those with an A. P. I. gravity range of about 27.5 to 42.5 at 60/60 Rand with an initial boiling point (A. S. T. M. method) ranging from about 210 F. to 355 Fe, and an end point ranging from about 240 F. to 415 F. I have also had excellent results using straight toluene (commercial grade), ,as well as benzene. Examples of still other suitable solvents are the ,xylenes (ortho, ,meta and para) and the other homologs of benzene such as ethylbenzene,propylbenzene, isopropylbenzene (cumene), pseudocumene and mesitylene. I have also prepared several batches of the additive using kerosene as the solvent; also gasoline, both leaded and unleaded. Thesame deep red color was obtained in the clear liquid and the engines withwhich it was used ran with substantially-the same smoothness as when the solvent employed -was of the aforesaid aromatic hydrocarbon-type. While there may be a possibility of some urea adductformation with kerosene and gasoline as the solvents it is'believed, as explainedhereinabove, that such is not formed in anysubstantial amount Considerable latitude may be exercised in the relative amounts of the alcohols and ketones or-aldehydes employed as well as the amount of solventused in conjunction therewith to constitute the three-component liquid mixture to be: contacted with the urea and alkali-metal hydroxide. I have employed a mixture of -the three liquids wherein the alcohol and the ketone oraldehyde were each as low as 12 /2 %,'the solvent -used therewith comprising the remaining Withsuch a mixture the rgulting ,red liquid was of a less dense red C0101 than that obtained with higher contents of alcohol and kctone, but upon distilling out the solvent the redicolor deepened. With *5,0%;solvent, 25% alcohol and 25% lretone or aldehyde, the resulting redliquid-is substantially all soluble ingasoline and diesel motor fuels and the etfect upon engine performance is substantially thesame as when the solvent, alcohol and ketone are in equal volumes, i. e. 33 /s% each, in the liquid mixture contacted with the urea and alkalimetal-hydroxide. The amount of solvent employed should preferably besuch as to give complete solubility of the-redliquid formed in gasoline and diesel fuels. Generallyjitshould not fall far below about 25% of the entire liquidmixture of solvent, alcohol and ketone or aldehydecmploycd for desirable solubility of thered liquid in the motor fuels. With such low content ofsolvent in the mixture the alcohol and ketone content may each be in the neighborhood of 37 /2%, or they may vary therefrom withrespect to each other. My experimentsindicate that with an-amount of either alcohol or ketone less than 10% of the three-component liquid mixture an insu fficient amount of desired reaction product would be-produced. In this-connection-it has been observed that when'theamount of ketone exceeds the amount of alcohol the clear red liquid formed is of a'deeper red color. I prefer to use a liquid mixture in which the three components are in approximately equal volumes, i. e. 33 /3 for each.

As regards the alkali metalhydroxides, I have found v the type of fuel employed.

quire less whereas with the heavier fuels greater dosages games that potassium hydroxide may be used in. lieu of the sodium hydroxide hereinabove referred to. With lithium hydroxide I have experienced somewhat poor solubility in the mixture as well as poor engine performance. Ammonium hydroxide would not be satisfactory for the reason that thewater present would change the conditions making it necessary to apply heat to obtain reaction. Heat would also be necessary ifan alkali metal carbo nate were used and heat would bring about decomposition or otherwise interfere with the process.

With regard to the amount of urea and alkali metal hydroxide that may be used in proportion to the amount of liquid mixture of alcohol, ketone and solvent employed, in the example first herein-above given which as stated, is for the production of one gallon of the clear red liquid, the amounts of urea and sodium hydroxide stated are in excess of that which enters into the reaction. If smaller quantities of urea are employed the clear red liquid formed is of somewhat lighter color. n the other hand when a larger amount of urea is used no deepening of the red color takes place, indicating that the reaction will go only so far regardless of higher proportions of urea present. My experiments indicate that for the liquid mixture in an amount as stated for the aforesaid example an upper limit of 20 oz. of urea would be sufiicient to attain a maximum amount of reaction. For satisfactory practical results the amount of urea, for the aforesaid amount of liquid mixture should not be less than about 6 ounces. In general the amount of urea may range from a maximum of about 15% of the weight of the entire liquid mixture (solvent plus alcohol plus ketone) to a minimum of about of the weight of said liquid mixture. v

While the alkali metal hydroxide appears to act catalytically, the amount employed does have an efiect upon the rate of the reaction, it being faster with larger amounts. No harmful effects on the product formed result from the use of an excess of the alkali. If too little is used, the reaction is slowed. For satisfactory prac tical purposes, for the amount of liquid mixture added as per the example hereinabove given, the amount should not drop below about 1 ounce, whereas around ounces is an upper limit beyond which there would be no need to go. Thus the alkali metal hydroxide may rangefrom about one-half to one-sixth of the amount of urea.

With respect to the rate of use of the material as an additive for internal combustion engine fuel: When used in gasoline excellent results are obtained when it is employed at the rate of 1 cc. of the aforesaid red liquid in 10 gallons of gasoline. The increase in power output is so marked that I have found it advisable not to use it in amounts greater than 3 cc. in 10 gallons of gasoline, which is approximately 1 volume to 38,000 volumes of gasoline. Very satisfactory results have been obtained when it is employed at the rate of 0.5 cc. per 10 gallons of gasoline, i. e. at 1 volume to 76,000 volumes of gasoline.

When used in diesel fuels, a satisfactory rate ranges from 6 cc. to 12 cc. per 10 gallons of fuel depending on Lighter diesel fuels will recan be used for best results. Diesel fuels in general being heavier than gasoline, are harder to burn and give rise to more carbon formation, hence more of the additive is used than with gasoline. The additive is particularly beneficial in the starting of cold diesel engines, some diesel engines being extremely hard to start when cold.

The use of the clear red liquid prepared in accordance with the foregoing procedure from the stated materials gives an additive that is highly beneficial when used with either gasoline or hydrocarbon diesel fuels, giving marked smoothness of operation and increased power output in gasoline engines and in diesel engines. It is particularly pressing carbon deposition in both types of engines. Ad ditionally, it acts as a stabilizer against chlorine and bromine compounds that form from tetra ethyl lead contained in some gasoline. Being alkaline it inhibits or counteracts acid conditions resulting. from sulfur compounds in fuels, particularly in less refined diesel fuels. It is also particularly beneficial in the starting of cold diesel engines. This has been efiectively demonstrated in the operation over a period of twenty-two-months of two trucks each powered by a 150 H. P. Cumming engine. The starting of the engine of these trucks was improved remarkably when the diesel fuel contained the additive made in accordance with this invention. The trucks operaetd more smoothlyand seemed to have considerably more power on hills. At the conclusion of the 22-month operation with this additive, the engines were found to be clean. The fuel used in these diesel engines during this test period was a #2 furnace oil of about 32 gravity purchased from a major oil company.

The diesel engine fuel suitable for use with myadditive may be described broadly as petroleum distillates boiling in the range of from about 350 F. to about 750 F. Such distillates are ordinarily characterized by'an A. P. I. gravity of at least 20, and usually at least 25, the base stocks being either straight-run distillates or cracked distillates.

With respect to the fuel for spark ignition engines suitable for use with my additive, I have herein used the terms gasoline and hydrocarbon fuels boiling in the gasoline boiling range. These terms are intended to be usedinterchangeably and where the term gasoline is used both are understood to be embraced. These fuels have an A. S. T. M. distillation with an initial boiling point of about 100 F., and a final boiling point of about 400 F. and they may embrace for example straight run or cracked petroleum distillates, catalytically recracked gasoline dispronounced in preventing gum formation and in suptillate to convert olefinic constituents of the distillate, an alkylate (e. g. fuel (e. g. cumene, toluene, mand p-xylene, etc.), hydrogenated polymers (e. g. polymers of butene which, upon hydrogenation, have characteristics of isooctane, etc.), isopentane or butane, or a blend of two or more of such, or other, types of fuels.

Having thus describedmy inveniton, it will be understood that the invention embraces such variations and modifications as come within the spirit and scope thereof.

I claim:

1. The method of making an additive suitable for a spark ignition engine hydrocarbon fuel boiling in the gasoline boiling range and for a diesel engine fuel, which comprises admixing substantially fdry urea and a dry alkali metal hydroxide selected from the group consisting of sodium hydroxide and potassium hydroxide with a liquid mixture consisting essentially of an alcohol containing from three to five carbon atoms, a ketone containing up to six carbon atoms and a solvent selected from the group consisting of a petroleum distillate fraction having an A. S. T. M. distillation with an initial boiling point within the range of about 210 F. to 355 R, an end point wi.hin the range of about 240 F. to 415 F., an A. P. I. gravity within the range of about 27.5 to 42.5 at 60/ 60F. and an aromatic hydrocarbon content above about 50%, benzene, a horriolog of henzene, gasoline and kerosene, the amount of said'urea being within the range of from about 5% to 15% of the weight of said liquid mixture, the amount of said alkali metal hydroxide being within the. range of from about one-sixth to one-half of the weight of said urea, the said solvent component of said liquid mixture comprising from about 25% to about 75% by volume of said liquid mixture, and the alcohol and ketone components comprising each in excess of about 10% by volume of said liquid mixture, allowing the admixture to stand at ordinary room temperature until a clear reddish colored liquid is formed, and separating the resultant clear red liquid isoparafiin-olefin alkylate), an aromatic 7 from any newly formed solid material and residual material.

2. The method in accordance with claim l whergin the alkali metal hydroxide is sodium hydroxide.

3. The method in accordance with claim ;1 wherein the said solvent, component of said ,liquidpmixture is essentially toluene.

4. The method ,invaccordance with claim 1 wherein the said solvent component of saidpliquid.mixture is essentially a petroleum distillate traetion having an A. S. distillationwith an initial boiling point within the range of about 210 F. .to .355 F., an end point within the range of about 240 F.;to 415 R, an A.,P.l.

' gravity withinthe range of about-27.5 to 42.5 at 60/ 60 F.

and an aromatic hydrocarbon content aboyc about 50%,

5. An addition agent for spark ignition engine hydrocarbon fuel boiling within the gasoline boiling range and for diesel fuel, said addition agenthaving been prepared by admixing substantially dry urea-and a dry-alkali metal hydroxide selected from the group consisting ofsodium hydroxide and potassium hydroxide with a liquid mixture consisting essentiallyvof an alcohol containing from three to five carbon atoms,-a ketone containing up to six carbon atoms and a solvent selected fromthe group consisting of a petroleum distillate fraction having an A. S. T. M. distillation with an initial boiling point within the range of about 210 F. to 355 F., an end point within the range of about 240", F. to 415 F., an A. P. L gravity within the range of about 27.5 to 42.5 at 60/ 60 F. and an aromatic hydrocarbon content above about 50%, benzene, a homolog of benzene, gasoline andkerosene, the amount of said urea being within the range of from about 5% to of the weight of said liquid mixture. the amount of said alkali metal hydroxide being within the range of from about one-sixth to one-half of the weight of said urea, the said solvent component of said liquid mixture comprising from about to about 75% by volume of said liquid mixture, and the alcohol and ketone components comprising each in excess of about 10% by volume of said liquidmixture, allowing the admixture to stand at ordinary room temperature until a clear reddish colored liquid is formed, antiseparating the resultant clear red liquid from any newly formed solid materialand residual material.

6. An addition agent in accordance with claim 5 where in the solvent, the alcohol andthe ketone each constitutesabout 33%% by volume of the said liquid mixture employed in the preparationof said addition agent.

7. An addition agent in accordance with claim 5 wherein the solvent constitutes ;-,about 175% by volume of :the said liquid mixture employed ,inthe preparation of said addition agent and tthe alcohol andketone components of said liquid mixture are in;about equal volumes.

8. Anaddition agent in-accordance with claim 5 where-' z 10. An addition agent for spark ignition engine hydrocarbon fuel boiling within the gasoline boiling range and for diesel fuel, said addition agent having been prepared by admixing substantially dry urea and a dry alkali metal hydroxide selected from the group consisting of sodium hydroxide and potassium hydroxide with a liquid mixture consisting essentially of an alcohol containing from three to five carbon atoms and a ketone containing up to six carbon atoms, the amount of said urea being within the range of from about 5% to 15% of the weight of said liquid mixture, the, amount of said alkali metal hydroxide being within the range of from about one-sixth to onehalf of the weight of said urea, the said alcohol and said ketone each constituting in excess of about 10% by volume of said liquid mixture, allowing the admixture to stand at ordinary room temperature until a clear reddish colored liquid is formed, separating the resultant clear red liquid from any newly formed solid material and residual material, and freeing said resultant clear red liquid of its water soluble portion.

11. An addition agent in accordance with claim 10 wherein the alcohol and ketone each constitutes about one-half by volume of said liquid mixture.

12. An addition agent for spark ignition engine hydrocarbon fuel boiling within the gasoline boiling range and for diesel fuel, said addition agent having been prepared by admixing substantially dry urea and a dry alkali metal hydroxide selected from the group consisting of sodium hydroxide and potassium hydroxide with a liquid mixture consisting essentially of an alcohol containing up to five carbon atoms, a ketone containing up to six carbon atoms anda solvent selected from the group consisting of a petroleum distillate fraction having an A.S.T.M. distillation with an initial boiling point within the range of about 210 F. to 355 R, an end point within the range of about 240 F. to 415 F., and A. P. I. gravity within the range of about 27.5 to 42.5 at 60 F. and an aromatic hydrocarbon content above about 50%, benzene, a homolog of benzene, gasoline and kerosene, the amount of said urea being within the range of from about 5% to 15% of the weight of said liquid mixture, the amount of said alkali metal hydroxide being within the range of from about one-sixth to one-half of the weight of said urea, the said solvent component of said liquid mixture comprising from about 25% to about by volume of said liquid mixture, and the alcohol and ketone components comprising each in excess of about 10% by volume of said liquid mixture, allowing the admixture to stand at ordinary room temperature until a clear reddish colored liquid is fonned, and separating the resultant clear red liquid from any newly formed solid material and residual material.

References Cited in the file of this patent UNITED STATES PATENTS 974,749 Caulfield Nov. 1, 1910 1,469,053 Schreiber Sept. 25, 1923 1,684,686 Records Sept. 18, 1928 2,002,645 Rather et al May 28, 1935 2,447,621 Smidth Aug. 24, 1948 2,529,784 Olin et a1. Nov. 14, 1950 FOREIGN PATENTS 562,091 Great Britain June 19, 1944 

1. THE METHOD OF MAKING AN ADDITIVE SUITABLE FOR A SPARK IGNITION ENGINE HYDROCARBON FUEL BOILING IN THE GASOLINE BOILING RANGE AND FOR A DIESEL ENGINE FUEL, WHICH COMPRISES ADMIXING SUBSTANTIALLY DRY UREA AND A DRY ALKALI METAL HYDROXIDE SELECTED FROM THE GROUP CONSISTING OF SODIUM HYDROXIDE AND POTASSIUM HYDROXIDE WITH A LIQUID MIXTURE CONSISTING ESSENTIALLY OF AN ALCOHOL CONTAINING FROM THREE TO FIVE CARBON ATOMS, A KETONE CONTAINING UP TO SIX CARBON ATOMS AND A SOLVENT SELECTED FROM THE GROUP CONSISTING OF A PETROLEUM DISTILLATE FRACTION HAVING AN A. S. T. M. DISTILLATION WITH AN INITIAL BOILING POINT WITHIN THE RANGE OF ABOUT 210*F. TO 335* F., AN END POINT WITHIN THE RANGE OF ABOUT 240*F. TO 415*F., AN A. P. I. GRAVITY WITHIN THE RANGE OF ABOUT 27.5 TO 42.5 AT 60/60*F. AND AN AROMATIC HYDROCARBON CONTENT ABOVE ABOUT 50%, BENZENE, A HOMOLOG OF BENZENE, GASOLINE AND KEROSENE, THE AMOUNT OF SAID UREA BEING WITHION THE RANGE OF FROM ABOUT 5% TO 15% OF THE WEIGHT OF SAID LIQUID MIXTURE, THE AMOUNT OF SAID ALKALI METAL HYDROXIDE BEING WITHIN THE RANGE OF FROM ABOUT ONE-SIXTH TO ONE-HALF OF THE WEIGHT OF SAID UREA, THE SAID SOLVENT COMPONENT OF SAID LIQUID MIXTURE COMPRISING FROM ABOUT 25% TO ABOUT 75% BY VOLUME OF SAID LIQUID MIXTURE, AND THE ALCOHOL AND KETONE COMPONENTS COMPRISING EACH IN EXCESS OF ABOUT 10% BY VOLUME OF SAID LIQUID MIXTURE, ALLOWING THE ADMIXTURE TO STAND AT ORDINARY ROOM TEMPERATURE UNTIL A CLEAR REDDISH COLORED LIQUID IS FORMED, AND SEPARATING THE RESULTANT CLEAR RED LIQUID FROM ANY NEWLY FORMED SOLID MATERIAL AND RESIDUAL MATERIAL. 